[bachster]

Except in the case of the FABRICATED brackets, R12 (ie, physical robot elements may not be created before kickoff) still applies, whereas COTS brackets acquired before kickoff could be used.

In this case it is unfortunate that the rules create a distinction between functionally equivalent parts, and seemingly discourage you from benefiting (and helping other teams benefit from) your sponsor's aid. However, if you take a hypothetical approach where the sponsor was including some special, proprietary feature on the brackets (like a fancy lightweight material) that only one team had access to, one can start to see the rationale for limiting the timeline for FABRICATED components.

It does seem like there could be room for "components functionally equivalent to COTS" where COTS rules could be applied, but capturing the intent while considering all end cases would be tough.